Editing Van de Graaff generator (section)

=== Initial development ===

The Van de Graaff generator was developed, starting in 1929, by physicist Robert J. Van de Graaff at [[Princeton University]], with help from colleague Nicholas Burke. The first model was demonstrated in October 1929.<ref>{{cite web |url=http://chem.ch.huji.ac.il/~eugeniik/history/graaff.html |title=Robert Jemison Van de Graaff |website=The Institute of Chemistry – The Hebrew University of Jerusalem |access-date=2006-08-31 |url-status=dead |archive-url=https://web.archive.org/web/20060904024639/http://chem.ch.huji.ac.il/~eugeniik/history/graaff.html |archive-date=2006-09-04}}</ref> The first machine used an ordinary tin can, a small motor, and a silk ribbon bought at a [[variety store#North America|five-and-dime store]]. After that, he went to the chairman of the physics department requesting $100 to make an improved version. He did get the money, with some difficulty. By 1931, he could report achieving 1.5 million volts, saying "The machine is simple, inexpensive, and portable. An ordinary lamp socket provides the only power needed."<ref>{{cite journal |last=van de Graaff |first=R. J. |title=Minutes of the Schenectady Meeting September 10, 11 and 12, 1931: A 1,500,000 volt electrostatic generator. |journal=Physical Review |publisher=American Physical Society (APS) |volume=38 |issue=10 |date=1931-11-15 |issn=0031-899X |doi=10.1103/physrev.38.1915 |pages=1919–1920}}</ref><ref>''Niels Bohr's Times'', Abraham Pais, Oxford University Press, 1991, pp.378-379</ref> According to a patent application, it had two 60-cm-diameter charge-accumulation spheres mounted on [[Pyrex|borosilicate glass]] columns 180&nbsp;cm high; the apparatus cost $90 in 1931.<ref>"Van de Graaff's Generator", in "Electrical Engineering Handbook", (ed), CRC Press, Boca Raton, Florida USA, 1993 {{ISBN|0-8493-0185-8}}</ref><ref>{{cite journal |last1=Wolff |first1=M.F. |title=Van de Graaff's generator |journal=IEEE Spectrum |date=July 1990 |volume=27 |issue=7 |pages=46 |doi=10.1109/6.58426|s2cid=43715110 }}</ref>

Van de Graaff applied for a second patent in December 1931, which was assigned to [[Massachusetts Institute of Technology]] in exchange for a share of net income; the patent was later granted.<ref>{{cite journal |title=This Month in Physics History: February 12, 1935: Patent granted for Van de Graaff generator |journal=APS News |date=February 2011 |volume=20 |issue=2 |url=https://www.aps.org/publications/apsnews/201102/physicshistory.cfm |access-date=10 May 2022}}</ref>

In 1933, Van de Graaff built a 40&nbsp;ft (12&nbsp;m) model at MIT's [[Round Hill, Massachusetts|Round Hill]] facility, the use of which was donated by [[Edward Howland Robinson Green|Colonel Edward H. R. Green]].<ref>{{cite journal |last1=Thomas |first1=William |title=A profile of John Trump, Donald's accomplished scientist uncle |journal=Physics Today |date=7 September 2016 |issue=9 |page=22954 |doi=10.1063/PT.5.9068 |bibcode=2016PhT..2016i2954T |url=https://physicstoday.scitation.org/do/10.1063/pt.5.9068/full/ |access-date=10 May 2022}}</ref> One consequence of the location of this generator in an aircraft hangar was the "pigeon effect": arcing from accumulated droppings on the outer surface of the spheres.<ref>{{cite web |last1=Wilson |first1=E.J.N. |title=Overview of Accelerators |url=https://acceleratorinstitute.web.cern.ch/ACINST1112/Lecture1(OverviewI).pdf |website=Accelerator Institute |publisher=CERN |access-date=10 May 2022}}</ref>